This article explains the vSAN object format health check in the vSAN Health Service and provides details on why it reports an issue.

VMware vSAN 7.0.x
VMware vSAN 8.0.x

Q: What does the 'vSAN object format health' check do?

This health check verifies if any existing objects on vSAN needs to be converted to the new object format - it also shows the amount of objects using older format and total bytes to move.

Those listed objects are in an old object format and all objects larger than > 255GB will be taken into account. The "Object Count" column counts both objects need to be reformatted and objects that are in reformatting process while "Total Bytes to Move" column only calculates the bytes to be reformatted.

Q: Why object format needs to be changed?

Objects in new format reduce the operation reserve space that needs to be maintained in the cluster to allow vSAN to complete its internal operations (for example, more flexible resynchronization processes).

Q: What does it mean if it shows a warning state?

It means there are some objects need to be reformatted. Without reformat, some of the new features may be unusable.

Q: How to fix this warning?

Click the "Change Object Format" button to trigger the reformat process and wait for its completion.

This process may take a long time depending on the amount of data that needs to be moved. The process will also take up additional storage space during the rebuild of the objects. Higher network and disk load is expected.

Q: Is there anything to pay attention to?

As this puts additional load on your vSAN cluster, this can result in slightly higher storage latencies depending on the overall performance and utilization of your environment. Therefore, it is recommended to perform those actions during a maintenance window or outside the main business hours.

Please ensure your vSAN datastore utilization is below at least 80%, best being at or below 70% to allow vSAN to efficiently perform its operations.